Modified Styrene Butadiene Rubber (SBR) polymer/asphalt compositions are known to those skilled in the art. Polymer modified asphalt blends are useful for paving materials, roofing materials, products for protection of car bottoms and other coating applications. Asphalt/polymer blends must have good phase compatibility between the asphalt and the polymer, and must be storage stable at high temperatures for ease of handling and application. Specifically, U.S. Pat. No. 4,333,866 discloses a rubber modified asphalt composition containing styrene butadiene rubber (SBR) and asphalt and a vinyl aromatic monomer such as cinnamic acid. U.S. Pat. No. 5,451,619 discloses an asphalt composition containing styrene butadiene rubber which is epoxidized. Said composition is said to exhibit better compatibility than previous polymer modified compositions. U.S. Pat. No. 5,604,274 discloses a blend of asphalt and epoxy functionalized polymer. Styrene/butadiene rubber is not disclosed as part of the composition. U.S. Pat. No. 5,574,095 discloses an asphalt composition containing epoxy or glycidyl functional polymers. Styrene/butadiene is not disclosed as part of the composition. U.S. Pat. No. 5,672,642 discloses a process for preparing asphalt polymer blends comprising contacting sulfur with asphalt and contacting a polymer with the sulfur asphalt mixture. The preferred polymer is a styrene-butadiene-styrene block copolymer. U.S. Pat. No. 5,331,028 discloses a rubber modified composition containing block styrene butadiene rubber, asphalt and a glycidyl containing ethylene copolymer wherein the glycidyl moiety refers to an epoxide containing functionality. Finally, U.S. Pat. No. 4,772,647 discloses aqueous asphaltic emulsions wherein the asphaltic component is either a chemically modified asphalt or an asphalt-elastomer blend, and the aqueous component contains an acrylamide as an additive. Either type of emulsion can be utilized as a coating composition, i.e., as a basement waterproofing spray, or as a crack filler for highway and related uses. U.S. Pat. No. 5,710,196 discloses an asphalt composition comprising:
(i) an asphalt and PA1 (ii) a graft copolymer resin comprising a rubbery polymeric substrate and a rigid polymeric substrate, wherein the rubbery substrate and rigid substrate optionally contain acrylamide. PA1 Wherein R.sub.1 =H or CH.sub.3, R.sub.2 =H , C.sub.1-4 alkyl group or a phenyl group, R.sub.3 =H, C.sub.1-4 alkyl group or a phenyl group PA1 wherein n=10-30, preferably n=20. PA1 (a) 1 to 30% random vinyl substituted aromatic/C.sub.4 -C.sub.6 conjugated diolefin polymer PA1 (b) 70 to 99% asphalt; and PA1 (c) 0.1 to 10% of a modifier selected from the group consisting of keto-containing amides, an oxazoline containing copolymer, or an ethoxylated trimethylolpropane triacrylate or mixtures thereof. PA1 (a) 1 to 30% random vinyl substituted aromatic/C.sub.4 -C.sub.6 conjugated diolefin polymer PA1 (b) 70 to 99% asphalt; and PA1 (c) 0.1 to 10% of a modifier selected from the group consisting of keto-containing amides, an oxazoline containing copolymer, or an ethoxylated trimethylolpropane triacrylate or mixtures thereof.
U.S. Pat. No. 5,733,955 discloses that rubbery terpolymers of a conjugated diolefin monomer (butadiene), a vinyl aromatic monomer (styrene), a N-(isobutoxymethyl) acrylamide (IBMA) can be used to modify asphalt cement to greatly enhance the resistance to shoving, rutting, and low temperature cracking of asphalt concretes. U.S. Pat. No. 5,047,457 discloses an acrylate modified asphalt composition. Further, a number of patents cited therein describe the modification of the asphalt mixtures with, copolymers and interpolymers of alkyl acrylates and alkyl methacrylates with olefinic monomers such as ethylene, e.g. U.S. Pat. Nos. 2,972,588; 3,414,533; 3,980,598; 4,492,781; and 4,511,689.
The use of acrylates as asphalt modifiers is also disclosed in U.S. Pat. No. 3,951,895, U.S. Pat. No. 4,018,730 and U.S. Pat. No. 4,222,916. U.S. Pat. No. 3,951,895 describes asphaltic compounds for use in paving and roofing in which an acrylic emulsion of a copolymer of methyl methacrylate and ethylacrylate is mixed with 1 to 3 parts of hydrated lime and 40 parts of sand. This acrylic emulsion then is blended with an asphalt emulsion. U.S. Pat. No. 4,018,730 describes methods for emulsifying asphalt-rubber paving materials. The rubber materials which may be included in the asphalt paving material include a wide variety of natural as well as synthetic rubbers including acrylic rubber. U.S. Pat. No. 4,222,916 describes coal tar emulsions containing sufficient acrylate emulsions to provide a desired viscosity. The acrylate emulsion is exemplified by butyl acrylate.
Surprisingly, Applicants have discovered a polymer modified asphalt hot mix system wherein the modifier is a keto-containing amide functional monomer, such as diacetone acrylamide (DAAM), or an oxazoline containing copolymer, or an ethoxylated trimethylolpropane triacrylate, or mixtures thereof.